You may often hear advice about limiting the amount of sugar we eat. But information about the different types of sugar we might consume isn’t talked about as widely, so it’s natural that you might have questions. In this post we’ll look at a type of sugar called fructose and explore some of the effects of consuming too much of it.
What is fructose?
Fructose is a type of sugar. It’s a monosaccharide, which is the simplest form of carbohydrate and consists of one unit of sugar, hence the more colloquial term ‘simple sugar’. Simple sugars like fructose can be used to build more complex carbohydrates. For example, fructose can bind to glucose to create sucrose, or what we know as table sugar. Pure fructose is very sweet.
Fructose is found in many whole foods, including fruits, vegetables and honey, and can be a natural sugar if you consume it from these sources. Examples of fruits and vegetables high in fructose include:
- Apples
- Bananas
- Blueberries
- Eggplant
- Grapes
- Jackfruit
- Pears
- Raisins
- Red bell peppers
- Summer squash
- Sweet onions
Consuming fructose through these foods isn’t considered unhealthy unless you eat excessive amounts, or have a fructose intolerance (where the body is unable to break fructose down). Fruits and vegetables are rich in fiber, vitamins, minerals and antioxidants. Fiber helps us with digestion, while vitamins and minerals are nutrients the body needs to stay healthy. Antioxidants help to balance free radicals in the body.
However, fructose can also be an added sugar, if you consume it from packaged foods and drinks which have had fructose or sweeteners containing fructose added to them, such as:
- Candy
- Fast food
- Fruit jams and jellies
- Ice cream and ice pops
- Juice drinks
- Packaged baked goods, like cakes, cookies, pastries and pies
- Ready-made meals
- Ready-made sauces and condiments
- Ready-made salad dressings
- Sodas
- Sweetened fruit yogurt
We’re most likely to consume fructose through table sugar (also known as sucrose), which fructose is often added to, and high-fructose corn syrup, which is found in processed foods like the ones above.
What is high-fructose corn syrup?
High-fructose corn syrup is a mixture of fructose and glucose, normally 42% or 55% fructose, and the rest made up of glucose and water. It’s an artificial added sugar used in many packaged foods and beverages.
What’s the difference between fructose and glucose?
Even though fructose and glucose are both simple sugars, our bodies process them in a different way. They can break glucose down in our cells, with the pancreas releasing insulin that allows cells to use the glucose for energy. Fructose is broken down in the liver and doesn’t trigger the release of insulin.
Why is fructose added to foods and beverages?
- The main thing fructose can add is sweetness. As it is sweeter than its counterparts, less of it is needed to get the same result.
- Fructose helps to retain moisture, which can improve the texture and extend the life of some processed foods.
- Fructose is very soluble, which means it dissolves well in water, and this makes it ideal for adding to beverages.
Is fructose bad for you?
There’s a lot of conflicting information out there about sugars and health. The Food and Drug Administration (FDA) says they are not aware of any evidence to suggest foods containing fructose or high-fructose corn syrup have any difference in safety compared to foods containing other sweeteners.
Fructose can be part of a nutritious diet if consumed through fruits, fruit juices, vegetables and honey. Less nutritious items, like soda and baked goods, can be enjoyed in moderation.
Everyone should limit sugar consumption, as recommended by the Dietary Guidelines for Americans, who state that “a healthy dietary pattern limits added sugars to less than 10 percent of calories per day”. They recommend the following daily calorie amounts for adults in the US. (Despite this, the US population consumes over 13% of total calories per day as added sugars.)
| Group | Recommended daily calories | 10% of recommended daily calories |
| Adult woman aged 19-30 | 1,800 – 2,400 | 180-240 |
| Adult women aged 31-59 | 1,600 – 2,200 | 160-220 |
| Adult women aged 60+ | 1,600 – 2,200 | 160-220 |
| Adult men aged 19-30 | 2,400 – 3,000 | 240-300 |
| Adult men aged 31-59 | 2,200 – 3,000 | 220-300 |
| Adult men aged 60+ | 2,000 – 2,600 | 200-260 |
With this in mind, let’s take a look at some of the potential problems consuming too much fructose can cause.
Weight gain
Studies into fructose consumption have drawn mixed conclusions, with some finding detrimental effects on health, while others finding no correlation. For example, consuming a lot of fructose may lead to obesity and an increase in body fat, according to one literature review. This is partly because fructose doesn’t trigger the hormones which tell our brains that we’ve had enough to eat, which means we may consume more than we need.
However, an earlier literature review found that fructose doesn’t do anything different to the body to cause weight gain compared to other sugar sources. The review also suggested that the high calories in foods and beverages containing fructose could be why there’s a link between fructose and weight gain.
Insulin resistance
Consuming high amounts of fructose can lead to inflammation, which in turn can lead to insulin resistance. Insulin resistance is when your cells stop responding properly to insulin and your pancreas produces more to compensate, increasing insulin and blood sugar levels. This can result in developing type 2 diabetes, where the body cannot use insulin the way it’s supposed to, and metabolic syndrome. Metabolic syndrome is a group of conditions, including high blood pressure, high blood sugar levels and low amounts of ‘good’ cholesterol, which can increase your risk of developing coronary heart disease, diabetes and stroke.
Liver problems
High intake of fructose can increase the risk of developing non-alcoholic fatty liver disease, notes the National Institutes of Health (NIH). Non-alcoholic fatty liver disease occurs when the body stores too much fat in the liver cells. It can cause damage and inflammation, but can be managed with gentle weight loss or even reversed in the early stage. Left unmanaged, it may lead to a condition called non-alcoholic steatohepatitis. This is more serious and can cause liver scarring, liver cancer, and liver failure.
You can reduce the chance of increasing liver fat by limiting your consumption of foods and beverages which contain fructose as an added sugar. One 2012 study found that men and women who drank soda with added sugar for six months saw a significant increase in the amount of liver fat they carried, compared to drinking beverages without added sugar (such as water, milk, and diet soda).
Cancer
Consuming too much fructose can increase the likelihood of developing intestinal tumors, according to research from a 2019 study and a 2021 study. However, it’s important to note that these studies were carried out on mice, not humans, and further research is needed before coming to a more definitive conclusion.
While none of the research so far has been conclusive, there is evidence to suggest that fructose can be bad for you when consumed in high amounts as an added sugar. However, it’s worth remembering that it’s difficult for researchers to know whether these negative effects are due to fructose or another type of sugar. This is because foods with added fructose also contain high amounts of these other sugars.
How much sugar should you consume per day?
There’s no specific recommendation for consuming fructose. However, the Dietary Guidelines for Americans recommends that added sugars should make up no more than 10% of the calories you consume per day.